The present invention relates to an apparatus for applying glue to a tubular core to fit in a re-reeling device for winding logs, in particular for material in paper strips.
In the field of preparation of rolls of toilet tissue, paper for household use and similar, denominated xe2x80x9clogsxe2x80x9d, the state of the art method is to distribute or position glue in various ways on an inner core of the log, so that the initial edge of the paper, fed in a re-reeling device, remains attached firmly to the core.
For this purpose, apparatus to apply glue to the tubular core to be fitted in a re-reeling device for winding logs are known in which the glue is fed by being forced through an opening parallel to a generatrix of a core.
This opening, for instance, is located above a chamber, at the end of a zone with slight pressure, from which there is a continual overflow of glue fed there by force.
In this way the glue comes into contact with the core, which in the meantime is pushed against the glue outlet opening by elements that prevent rotation to allow optimum reception of the glue.
For example, flexible plates are contemplated that yield as the tubular core passes and keep it in contact with the glue outlet opening, preventing rotation. A flat surface, located downstream of the opening, acts as a scraper for the glue deposited on the core which is fed without being able to rotate, this being prevented by the plates. In this way it must be noted that the glue is applied to the core in a non-symmetrical strip, which is thicker in the direction of feed.
The excess glue removed must then be returned to the tank to be subsequently returned under pressure by means of a pump towards the chamber and the outlet opening.
This device requires the plates to be positioned correctly with an elastic load that prevents the cores from rotating during the phase to receive the glue and during the phase to remove the excess glue.
In other apparatus the glue may be positioned in a strip, directed according to a generatrix zone of the core, by means of spray dispensers that foul the machine and do not guarantee a localized position of the glue.
Alternatively, the glue is positioned according to annular strips transverse to the cylindrical section of the core. However, this causes a certain quantity of glue and a certain quantity of paper material to remain unused and fixed by the glue to the core.
The object of the present invention is to produce an apparatus to apply glue to a tubular core to be fitted in a re-reeling device for winding logs, in particular for material in paper strips, which solves the problems of known art highlighted previously.
Another object is to provide an apparatus that is simpler and easier to produce in relation to those known heretofore.
Yet another object is to produce an apparatus to apply glue to a core that does not foul and does not require particular arrangements to re-feed excess glue.
These objects according to the present invention are obtained by producing an apparatus for applying glue to a tubular core to be fitted in a re-reeling device for winding logs as set forth herein.
Further relevant characteristics of the present invention are set forth in the related claims.